22 Oct 2024 | 09:35 AM UTC
US: Confirmed H5N1 avian influenza cases reported in California in October /update 1
Confirmed H5N1 avian influenza cases reported in California, US, in October. Avoid contact with poultry, wild birds, and cattle.
Health authorities have reported confirmed H5N1 avian influenza cases in California, with 13 cases reported Oct. 3-18. This is the first human H5 outbreak in the state. All cases are from Central Valley and had contact with infected dairy cattle. No person-to-person transmission has been detected in the state; only animal-to-human transmission has been confirmed. The risk is currently low for the general public. However, dairy or poultry farm workers and others who work with infected animals face a higher risk. Health officials recommend wearing personal protective equipment (PPE), such as N95 masks, eye protection, and gloves, for anyone working with infected or potentially infected animals. Additional cases are likely as monitoring and testing continue. This report represents the most complete data available as of Oct. 22.
Avoid contact with wild birds and live or recently dead poultry and cattle. Practice good hygiene, wear protective equipment when handling animals, clean surfaces thoroughly, cook poultry and eggs, and report any illness after exposure to a healthcare provider.
Since 2022, H5N1 has spread widely among wild birds, leading to persistent outbreaks in U.S. poultry. This year marked the first detection of the virus in cows. In August 2024, California reported an outbreak among dairy herds. The US has reported 27 human cases of H5 bird flu so far in 2024.
Avian influenza infections in humans usually occur among poultry workers, individuals in close contact with backyard poultry, or those visiting wet markets where live poultry are kept and slaughtered. There have also been cases involving individuals in close contact with infected cattle.
Avian influenza refers to diseases caused by infection with avian (bird) influenza Type A viruses, which rarely spread to humans. Many different viruses cause avian influenza, including the H5N1 subtype. H5N1 spreads through close contact with infected birds, contaminated environments, or infected cattle, and person-to-person transmission is rare.
Human H5N1 infection typically has severe symptoms, including high fever, cough, sore throat, and muscle aches. The infection may progress rapidly to severe respiratory illness (difficulty breathing or shortness of breath) and neurologic changes (altered mental status or seizures). Most individuals infected with the virus require hospitalization, and approximately 60 percent of known cases have been fatal.
